But a fascinating article in Salon reveals that a book by a Mormon "historian" deemed too extreme even by the modern conservative movement -- which argues that the U.S. constitution is based primarily on natural law -- has played a major role in Beck's "thinking."

For several years, Beck has actively promoted "The 5000 Year Leap," by the late Cleon Skousen, on his radio and TV shows, and he recently wrote the foreword for a newly-released edition of the book, which was first published in 1981.

For more on this singular figure from the annals of the American far-right -- who appeared for a while to have been consigned to ignominy -- and about Beck's strange rediscovery of him, read Salon's story.

Late Update: As reader J.S. notes, Beck isn't the only conservative leader with a taste for Skousen. In 2007, then-presidential candidate Mitt Romney expressed his affinity for his fellow Mormon.